Students who survived the South Korea ferry disaster have described how they were told to stay put and witnessed their friends being swept away.

There were 325 pupils from Dawon High School on board the Sewol, but only 75 survived when it sank in April this year.

The captain is among senior crew members on trial over the tragedy and could face the death penalty.

Testifying for the first time, one girl told the court in Ansan City, south of Seoul they had ignored the order to stay where they were on the ship until the boat had listed so badly the cabin door was above their head.

Families said the rescue and recovery effort was too slow

Another student, testifying via video link, described how the tannoy told them repeatedly to put on a life jacket and stay put.

"We were waiting and, when the water started coming in, the class rep told everyone to put on the life vests ... the door was above our heads, so she said we'll float and go through the door and that's how we came out," one of the teenagers said.

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Gallery: Scene Of Sewol Disaster

Hundreds of high school pupils were on board the Sewol when it got into difficulties - only 75 survived. Continue through the gallery for more images from the scene and the rescue effort.

"Other kids who got out before us pulled us out."

Another girl said no crew came to their aid and described how she and some friends escaped by climbing horizontally along a staircase and through an escape hatch.

But - as she jumped out - a sea swell engulfed the corridor.

"There were many classmates in the corridor and most of them were swept back into the ship," said the girl.

Five of the six female students giving evidence on Monday did so in person at a special court session close to the school. Seventeen students have agreed to appear at the two-day session.

Video:June: Survivors Back At School

The coastguard also waited outside the ferry for people to swim out, rather than venturing in themselves, claimed one witness, while another student told the court there were more fishermen helping than rescuers.

"They (the coastguard) were outside," said the girl. "They pulled us (onto boats) but they didn't come inside to help. We said to ourselves, 'why aren't they coming in?'."

The Sewol ferry, overloaded with cargo, sank off the southwest coast on April 16 on a routine journey from Incheon on the mainland to the southern holiday island of Jeju.

The students, who were on a school trip, made up the majority of the 476 people on board. The final death toll was 304, with 172 survivors.

Mobile phone footage emerged in the days after the tragedy which showed students struggling in the badly listing ferry and sending final messages to their loved ones.

Video:May 19, 2014: Tears Over Disaster

Captain Lee Joon-seok was photographed hopping onto a rescue boat while hundreds remained on board - he and three senior crew members are charged with homicide and could be executed.

Two other crew members are also accused of fleeing and abandoning ship, which carries a maximum sentence of life imprisonment, while nine have been charged with negligence.

Yoo Byung-eun had been on the run since April, but police are not year sure whether he was murdered or killed himself.

The vice-principal of Dawon High School also took his own life in the wake of the disaster, with a suicide note saying "surviving alone is too painful ... I take full responsibility. I pushed ahead with the school trip."